JP2023066216A - Reduction gear - Google Patents

Abstract

To provide an eccentric oscillating type reduction gear having structure in which seizure hardly occurs at a meshing portion of an internal gear and an external gear.SOLUTION: A first rotary portion rotates around a central axis at a first number of revolutions. An eccentric portion is disposed in a radial outside of the first rotary portion, rotates together with the first rotary portion, and distance from the central axis to an outer peripheral surface is different depending on a circumferential position. An externally toothed gear is disposed in a radial outside of the eccentric portion via a bearing. A cylindrical frame is disposed in a radial outside of the externally toothed gear and also disposed coaxially with the central axis. A plurality of internal tooth pins is held in parallel in an axial direction by an inner peripheral portion and meshed with the externally toothed gear. A carrier pin extends in the axial direction passing through a plurality of through-holes disposed in the externally toothed gear. A second rotary portion is fixed to the plurality of carrier pins. The frame has a first groove portion and a second groove portion. The first groove portion is recessed to radial outside from an inner peripheral surface and axially extends, and rotatably holds the internal tooth pins. The second groove portion is recessed to radial outside from the first groove portion.SELECTED DRAWING: Figure 3

Description

The present invention relates to a speed reducer.

2. Description of the Related Art Conventionally, an eccentric oscillating type (inscribed planetary type) speed reducer is known in which an external gear oscillates and internally meshes with a frame having internal teeth. In such a speed reducer, the rotation component of the external gear is taken out by a carrier pin that axially penetrates the external gear. This type of speed reducer is disclosed as a gear transmission in Japanese Patent No. 6335006, for example.

A gear transmission disclosed in Japanese Patent No. 6335006 includes an internal tooth member having an internal gear formed on the inner periphery thereof, and an external tooth member that rotates eccentrically relative to the internal gear while meshing with the internal gear. with gears; In the gear transmission disclosed in Japanese Patent No. 6335006, a plurality of grooves extend along the axis of the gear transmission and are provided at equal intervals in the circumferential direction on the inner peripheral surface of the internal tooth member. . The internal gear is constructed by inserting a cylindrical member into the groove. In the gear transmission disclosed in Japanese Patent No. 6335006, the axial end portion of the cylindrical member is greater than the axial intermediate portion of the cylindrical member in contact with the groove in the circumferential direction. It is said that the length is short.
Japanese Patent No. 6335006

In the gear transmission configured as described in Japanese Patent No. 6335006, of the outer peripheral surface of the cylindrical member, the surface exposed from the groove is lubricated with lubricating oil supplied to the internal space of the gear transmission. On the other hand, it was difficult to distribute the lubricating oil to the surface covered with the grooves in the outer peripheral surface of the cylindrical member. Therefore, in the gear transmission disclosed in Japanese Patent No. 6335006, seizure may occur at the meshing portion between the internal gear and the external gear, and there is room for improvement.

The present invention has been made in view of the above circumstances, and its potential purpose is to suppress seizure from occurring at the meshing portion between the external tooth and the internal tooth pin.

The problems to be solved by the present invention are as described above, and the means for solving the problems will now be described.

From the viewpoint of the present invention, an eccentric oscillating speed reducer includes a first rotating portion, an eccentric portion, an external gear, a bearing, a frame, a plurality of internal pins, and a second rotating portion. is provided. The first rotating portion rotates at a first rotation speed around the central axis. The eccentric portion is arranged radially outward of the first rotating portion, rotates at the same rotational speed as the first rotating portion, and has a different distance from the central axis to the outer peripheral surface depending on the position in the circumferential direction. The external gear is arranged radially outward of the eccentric portion and has a plurality of external teeth on its outer peripheral portion. The bearing is interposed between the eccentric portion and the external gear. The frame is cylindrical and arranged radially outward of the external gear and coaxial with the central axis. The plurality of internal tooth pins are held on the inner peripheral portion of the frame in a posture parallel to the axial direction and mesh with the external teeth. The carrier pin extends axially through a plurality of through holes provided in the external gear. The second rotating part is fixed to the plurality of carrier pins. The frame has a first groove and a second groove. The first groove portion is recessed radially outward from the inner peripheral surface and extends in the axial direction to rotatably hold the internal pin. The second groove is recessed radially outward from the first groove.

According to the aspect of the present invention, it is possible to lubricate the internal pin with the lubricating oil accumulated in the second groove. Therefore, it is possible to suppress the occurrence of seizing at the meshing portion between the external tooth and the internal tooth pin.

FIG. 1 is a longitudinal sectional view of an eccentric oscillating speed reducer according to the first embodiment. FIG. 2 is a cross-sectional view taken along the line II-II in FIG. 1, showing the state of the meshing portion. FIG. 3 shows the state of the first groove and the second groove when viewed in the axial direction. FIG. 4 shows the state of the first groove and the second groove when viewed in the axial direction in the eccentric oscillating type speed reducer according to the second embodiment. FIG. 5 shows the angular range in which the second grooves are arranged.

Exemplary embodiments of the invention are described below with reference to the drawings. In the present application, the direction parallel to the central axis of the speed reducer is referred to as "axial direction", the direction orthogonal to the central axis is referred to as "radial direction", and the direction along the arc around the central axis is referred to as "circumferential direction". called. However, the above-mentioned "parallel direction" also includes substantially parallel directions. Moreover, the above-mentioned "perpendicular direction" also includes substantially perpendicular directions.

<1. First Embodiment>
<1-1. Overall configuration of speed reducer>
FIG. 1 is a longitudinal sectional view of a speed reducer 1 according to a first embodiment of the invention. FIG. 2 is a cross-sectional view of the speed reducer 1 viewed from the II-II position in FIG.

This speed reducer 1 is an eccentric oscillating type (internal planetary) gear reducer. The speed reducer 1 is used, for example, as a joint of a small robot such as a service robot that works in cooperation with humans. However, speed reducers of equivalent construction may be used in other applications such as large industrial robots, machine tools, XY tables, material cutting equipment, conveyor lines, turntables, rolling rollers, and the like.

As shown in FIG. 1, the speed reducer 1 of the present embodiment includes a first rotating portion 10, two eccentric portions 20, two external gears 30, two first bearings (bearings) 91, a frame 50, a plurality of inner tooth pin 60 , a plurality of carrier pins 70 and a second rotating part 80 .

The first rotating part 10 is a cylindrical member extending along the central axis C. As shown in FIG. The first rotating part 10 is connected to a motor, which is a driving source, directly or via another power transmission mechanism. When the motor is driven, the power supplied from the motor causes the first rotating portion 10 to rotate about the central axis C at the first rotation speed. That is, in this embodiment, the first rotating section 10 serves as an input section.

The eccentric portion 20 is a portion that rotates together with the first rotating portion 10 at the same rotational speed as the first rotating portion 10 . The two eccentric portions 20 are arranged axially apart from each other on the outer peripheral portion of the first rotating portion 10 . In this embodiment, the first rotating portion 10 and the two eccentric portions 20 are made of a single member. However, the first rotating portion 10 and the two eccentric portions 20 may not be a single member. Each of the two eccentric portions 20 has a cylindrical outer peripheral surface centered on an eccentric axis D extending parallel to the central axis C at a position off the central axis C. As shown in FIG. Therefore, the distance from the central axis C to the outer peripheral surface of the eccentric portion 20 varies depending on the position in the circumferential direction. When the first rotating portion 10 rotates about the central axis C, the positions of the two eccentric portions 20 rotate about the central axis C. As shown in FIG. At this time, the eccentric axis D of each eccentric portion 20 also rotates around the central axis C. As shown in FIG.

In this embodiment, the position of the eccentric axis D of one eccentric portion 20 and the position of the eccentric axis D of the other eccentric portion 20 are separated from each other by 180° with respect to the central axis C. As shown in FIG. In this way, the center of gravity of the two eccentric portions 20 as a whole is always located on the central axis C. Therefore, fluctuation of the center of gravity due to rotation of the eccentric portion 20 can be suppressed.

The two external gears 30 are arranged radially outward of the eccentric portion 20 . A first bearing 91 is interposed between the eccentric portion 20 and the external gear 30 . A known bearing such as a roller bearing can be used for the first bearing 91 . The external gear 30 is rotatably supported around the eccentric axis D by the first bearing 91 . As shown in FIG. 2 , a plurality of external teeth 31 are provided on the outer peripheral portion of the external gear 30 . Each external tooth 31 protrudes radially outward. Further, between adjacent external teeth 31, grooves 32 between external teeth are provided that are recessed radially inward. In this embodiment, the grooves 32 between the external teeth when viewed in the axial direction are arc-shaped having a center point on a virtual circle centered on the eccentric axis D. As shown in FIG. In other words, the grooves 32 between the external teeth have a shape in which the outer peripheral surface of the external gear 30 is cut out at equal intervals in a semicircular shape when viewed in the axial direction. The external tooth 31 is a portion at a phase position that is not cut away when viewed in the axial direction. The external teeth 31 and the grooves 32 between the external teeth are alternately arranged in the circumferential direction with the eccentric axis D as the center.

1 and 2, each of the two external gears 30 has a plurality (eight in the example of FIG. 2) of through holes 33. As shown in FIG. Each through hole 33 axially penetrates the external gear 30 . The plurality of through-holes 33 are arranged around the eccentric axis D at regular intervals in the circumferential direction.

The frame 50 is a cylindrical member that surrounds the radially outer side of the two external gears 30 . The frame 50 is arranged coaxially with the central axis C. As shown in FIG. As shown in FIG. 2, a first groove portion 51 is provided in the inner peripheral portion of the frame 50 . In this embodiment, the first groove portion 51 when viewed in the axial direction has an arc shape having a center point on an imaginary circle centered on the central axis C. As shown in FIG. Each first groove 51 extends axially on the inner peripheral surface of the frame 50 . An internal pin 60, which will be described later, is held in the first groove portion 51 as an internal tooth. The first grooves 51 are provided at equal intervals on the inner peripheral portion of the frame 50 when viewed in the axial direction. In the inner peripheral portion of the frame 50 , portions between the adjacent first groove portions 51 become spaces 59 between inner tooth grooves. The first groove portions 51 and the inner tooth spaces 59 are alternately arranged in the circumferential direction with the central axis C as the center.

The internal pin 60 is a cylindrical member extending in the axial direction. The axial length of the internal pin 60 is substantially the same as the axial length from one end face of one external gear 30 to the other end face of the other external gear 30 . The internal tooth pin 60 is held on the inner peripheral portion of the frame 50 in a posture parallel to the axial direction. Specifically, the internal pin 60 is rotatably held in the first groove portion 51 of the frame 50 . The end of the internal tooth pin 60 is held by a holding member 69 fixed to the frame 50 . This prevents the internal pin 60 from falling out of the first groove portion 51 . As shown in FIG. 2 , the internal pin 60 held in the first groove portion 51 protrudes radially inward from the inner peripheral surface of the frame 50 .

A portion of the multiple external teeth 31 of the external gear 30 and a portion of the multiple internal pins 60 held by the frame 50 mesh with each other. Specifically, a portion of the internal pin 60 held by the frame 50 fits into a portion of the external inter-tooth groove 32 of the external gear 30 .

When the first rotating portion 10 rotates around the central axis C, the external gear 30 revolves around the central axis C together with the eccentric axis D. As shown in FIG. At this time, the external gear 30 revolves while displacing the meshing position between the external teeth 31 of the external gear 30 and the internal teeth (internal pin 60) of the frame 50 in the circumferential direction. Here, the number of internal pin 60 held by frame 50 is slightly larger than the number of external teeth 31 of external gear 30 . Therefore, for each revolution of the external gear 30, the position of the external tooth 31 that meshes with the internal pin 60 at the same position on the frame 50 shifts by the difference in the number of teeth. As a result, the external gear 30 rotates around the eccentric axis D in a direction opposite to the rotation direction of the first rotating portion 10 at a second rotation speed lower than the first rotation speed. Along with this, the position of the through hole 33 of the external gear 30 also rotates at the second rotation speed. When the speed reducer 1 operates, each of the two external gears 30 performs rotational motion combining such revolution and rotation.

Assuming that the number of external teeth 31 of the external gear 30 is N, and the number of internal pins 60 held by the frame 50 is M, the reduction ratio P of the speed reducer 1 is P=(first rotation speed)/( second rotational speed)=N/(M−N). In the example of FIG. 2, N=59 and M=60, so the speed reduction ratio in this example is P=59. That is, the second rotation speed is 1/59 of the first rotation speed. However, the number N of external teeth 31 and the number M of internal teeth pins 60 may be other values.

The plurality of carrier pins 70 are substantially cylindrical members extending axially through the two external gears 30 . A plurality of carrier pins 70 are arranged in an annular shape with central axis C as the center. Each carrier pin 70 is inserted into the through holes 33 of the two external gears 30 . A bush ring 71 is interposed between the outer peripheral surface of the carrier pin 70 and the inner peripheral surface of the through hole 33 . As shown in FIG. 2 , there is a gap (play) between the outer peripheral surface of the bushing ring 71 and the annular inner peripheral hole of the through hole 33 . As a result, when the two external gears 30 rotate at the second rotational speed after deceleration, the plurality of carrier pins 70 are pushed by the inner peripheral surfaces of the through holes 33 of the external gears 30 so that the plurality of carrier pins 70 also rotate on the central axis. It rotates around C at a second rotation speed.

Return to FIG. The second rotating portion 80 has an annular front carrier member 81 and an annular rear carrier member 82 . The front carrier member 81 is arranged on one side of the two external gears 30 in the axial direction. A second bearing 92 is interposed between the first rotating part 10 and the front carrier member 81 . A third bearing 93 is interposed between the front carrier member 81 and the frame 50 . The rear carrier member 82 is arranged on the other side in the axial direction of the two external gears 30 . A fourth bearing 94 is interposed between the first rotating portion 10 and the rear carrier member 82 . A fifth bearing 95 is interposed between the rear carrier member 82 and the frame 50 . Ball bearings, for example, are used for the second bearing 92 and the fourth bearing 94 . Angular ball bearings, for example, are used for the third bearing 93 and the fifth bearing 95 .

One axial end of each carrier pin 70 is fixed to the front carrier member 81 . The other axial end of each carrier pin 70 is fixed to a rear carrier member 82 . Therefore, when the plurality of carrier pins 70 rotate about the central axis C at the second rotational speed, the front carrier member 81 and the rear carrier member 82 also rotate about the central axis C at the second rotational speed. As a method for fixing the carrier pin 70 to the front carrier member 81 and the rear carrier member 82, for example, press fitting is used.

The second rotating part 80 is connected to a member to be driven, either directly or via another power transmission mechanism. That is, in this embodiment, the second rotating section 80 serves as an output section. With such a configuration, in the speed reducer 1 of the present embodiment, the rotation input to the first rotating portion 10 can be greatly reduced, and the rotation after deceleration can be extracted from the second rotating portion 80 .

Conventionally, in the speed reducer configured as described above, lubrication such as grease is applied to the radially inner space of the frame in order to suppress seizure at the meshing portion between the external tooth and the internal tooth pin. It was common to supply oil. With this configuration, the surface of the outer peripheral surface of the internal pin that is exposed from the groove that holds the internal pin can be lubricated with lubricating oil. However, it is difficult to distribute lubricating oil to the surface covered with the groove portion of the outer peripheral surface of the internal pin, and there is room for improvement.

<1-2. Detailed Configuration of Inner Periphery of Frame>
In this regard, the speed reducer 1 of the present embodiment has a unique configuration for spreading lubricating oil over the entire outer peripheral surface of the internal pin 60 . This particular configuration is described below with reference to FIG. FIG. 3 shows a portion of the inner periphery of frame 50 when viewed in the axial direction.

As shown in FIG. 3 , a second groove 52 is further provided in addition to the first groove 51 on the inner circumference of the frame 50 . The second groove portion 52 is recessed radially outward from the first groove portion 51 . The first groove portion 51 has a substantially semicircular shape when viewed in the axial direction. The second groove portion 52 is provided at a phase position corresponding to the middle point of the arc of the first groove portion 51, more specifically, the midpoint M of the arc of the first groove portion 51 when viewed in the axial direction. The second groove portion 52 is formed over the entire area of the first groove portion 51 in the axial direction. In other words, the second groove portion 52 is provided from one end to the other end in the axial direction of the first groove portion 51 .

The second groove portion 52 has an arcuate shape having a center point substantially overlapping a virtual curve passing over the semicircular curved surface of the first groove portion 51 when viewed in the axial direction. The position of this center point substantially coincides with the position of the midpoint M described above. The second groove portion 52 of this embodiment has a substantially semicircular shape when viewed in the axial direction.

When viewed in the axial direction, the end of the second groove portion 52 on one side in the circumferential direction is in an angle range up to a predetermined angle (for example, 20°) from the midpoint M to the one side in the circumferential direction with the center point N as the center. located in Further, when viewed in the axial direction, the end portion of the second groove portion 52 on the other side in the circumferential direction extends from the center point N to the other side in the circumferential direction by a predetermined angle (for example, 20°) from the midpoint M. located in the angular range. In FIG. 5, the angle range in which the second groove portion 52 is arranged is indicated by a double arrow.

In the speed reducer 1 configured as described above, lubricating oil such as grease is applied to the second groove portion 52 of the frame 50 when the members constituting the speed reducer 1 are assembled. As a result, the lubricating oil accumulates in the second groove portion 52 . In the speed reducer 1 assembled in this manner, the internal pin 60 is lubricated not only from the radially inner side but also from the radially outer side. That is, the area of the outer peripheral surface of the internal pin 60 covered with the first groove portion 51 can be lubricated by the lubricating oil from the second groove portion 52 . In particular, in the present embodiment, among the phase positions of the outer peripheral surface of the internal pin 60, conventionally, lubricating oil is most difficult to reach the center of the curved surface of the first groove portion 51. The surface can be lubricated. As a result, it is possible to effectively suppress the occurrence of seizure at the meshing portion between the external tooth 31 and the internal tooth pin 60 .

Moreover, in the present embodiment, the second groove portion 52 is not provided in a portion other than the central portion of the curved surface of the first groove portion 51 when viewed in the axial direction. In other words, of the curved surface of the first groove portion 51, both sides in the circumferential direction are not provided with structures such as grooves. Therefore, the torque applied to the internal pin 60 when the tooth trace of the external tooth 31 hits the pin 60 is supported by the curved surface of the first groove portion 51 . That is, the second groove portion 52 is provided within the area above the first groove portion 51 within a range that does not hinder torque transmission. As described above, in the present embodiment, lubricating oil is more easily supplied to the internal pin 60 than in the conventional art, and the transmission of torque to the internal pin 60 is not hindered. 60 is easy to rotate in the circumferential direction. As a result, the resistance in meshing between the external tooth 31 and the internal tooth pin 60 can be reduced, and the efficiency of the speed reducer 1 can be improved.

As described above, the speed reducer 1 of the present embodiment includes the first groove portion 51 that rotatably holds the internal pin 60 and the second groove portion 52 that is recessed radially outward from the first groove portion 51. have. Therefore, the internal tooth pin 60 can be lubricated by the lubricating oil accumulated in the second groove portion 52 . Therefore, it is possible to suppress the occurrence of seizure at the meshing portion between the external tooth 31 and the internal tooth pin 60 .

Further, in the speed reducer 1 of the present embodiment, the first groove portion 51 has an arc shape when viewed in the axial direction. Therefore, the inner tooth pin 60 can be rotatably supported by the arc-shaped curved surface of the first groove portion 51 .

Further, in the speed reducer 1 of the present embodiment, the first groove portion 51 has a semicircular shape when viewed in the axial direction. Therefore, the internal pin 60 can be stably held by the semicircular deep curved surface of the first groove portion 51 .

In addition, in the speed reducer 1 of the present embodiment, the second groove portion 52 is positioned in the middle of the arc of the first groove portion 51 when viewed in the axial direction. Thus, by arranging the arc-shaped curved surface of the first groove portion 51 in a region where force is likely to be applied due to the meshing of the external tooth 31 and the internal tooth pin 60, torque can be transmitted satisfactorily. can be done.

Further, in the speed reducer 1 of the present embodiment, the second groove portion 52 is arranged at a phase position corresponding to the midpoint M of the arc of the first groove portion 51 when viewed in the axial direction. As a result, the lubricating oil can be supplied to the internal pin 60 at the phase position where it was most difficult for the lubricating oil to reach. As a result, it is possible to effectively suppress the occurrence of seizure at the meshing portion between the external tooth 31 and the internal tooth pin 60 .

Furthermore, in the speed reducer 1 of the present embodiment, the second groove portion 52 is formed over the entire area of the first groove portion 51 in the axial direction. As a result, the internal tooth pin 60 can be lubricated with the lubricating oil accumulated in the second groove portion 52 over the entire area in the axial direction.

Furthermore, in the speed reducer 1 of the present embodiment, the second groove portion 52 has an arc shape when viewed in the axial direction. More specifically, the second groove portion 52 has a deep arcuate shape, more specifically a semicircular shape, when viewed in the axial direction. Thereby, the lubricating oil can be easily accumulated in the second groove portion 52 .

<2. Second Embodiment>
Below, the speed reducer 2 according to the second embodiment of the present invention will be described with reference to FIG. FIG. 4 shows the inner peripheral portion of the frame 50 of the speed reducer 2 according to the second embodiment. The speed reducer 2 of the present embodiment differs from the speed reducer 1 of the first embodiment in that it has a second groove portion 152 instead of the second groove portion 52 . Below, members having the same configuration and function as those shown in the first embodiment are denoted by the same reference numerals, and overlapping explanations are omitted.

As shown in FIG. 4 , a second groove 152 is provided in addition to the first groove 51 on the inner periphery of the frame 50 . The second groove portion 152 is recessed in a triangular shape radially outward from the first groove portion 51 when viewed in the axial direction. The second groove portion 152 has two inclined surfaces 53 and 54 when viewed in the axial direction. The second groove portion 152 is provided at a phase position corresponding to the middle point of the arc of the first groove portion 51, more specifically, the midpoint M of the arc of the first groove portion 51 when viewed in the axial direction. When viewed in the axial direction, the inclined surfaces 53 and 54 have They are symmetrical to each other. One inclined surface 53 approaches the curved surface of the first groove portion 51 as it goes from the phase position of the midpoint M of the arc of the first groove portion 51 toward one side in the circumferential direction of the circle centered at the center point N. , is slanted. The other inclined surface 54 approaches the curved surface of the first groove portion 51 as it goes from the phase position of the midpoint M of the arc of the first groove portion 51 toward the other side in the circumferential direction of the circle centered at the center point N. , is slanted.

When viewed in the axial direction, one end of the inclined surface 53 in the circumferential direction extends from the center point N to the one side in the circumferential direction at a predetermined angle (for example, 20°) from the midpoint M. positioned. Further, when viewed in the axial direction, the end portion of the inclined surface 54 on the other side in the circumferential direction extends from the center point N to the other side in the circumferential direction by a predetermined angle (for example, 20°) from the midpoint M. located in the range. In FIG. 5, the angle range in which the second groove portion 152 is arranged is indicated by a double arrow.

The second groove portion 152 can be easily provided by, for example, cutting. Therefore, it is possible to reduce the labor and cost of manufacturing. In the second groove portion 152 as well, the lubricating oil is accumulated in the same manner as the second groove portion 52 according to the first embodiment when the lubricating oil is applied in the assembly stage. As a result, it is possible to effectively suppress the occurrence of seizure at the meshing portion between the external tooth 31 and the internal tooth pin 60 .

As described above, the second groove portion 152 of the speed reducer 2 according to this embodiment has a triangular shape having two inclined surfaces 53 and 54 when viewed in the axial direction. Thereby, the shape of the second groove portion 152 can be easily processed.

Moreover, the second groove portion 152 is provided in a predetermined angular range around the center point N when viewed in the axial direction. That is, the second groove portion 152 is provided within the area on the first groove portion 51 within a range that does not contribute to torque transmission. As a result, the second groove portion 152 for lubrication of the internal pin 60 can be provided while the torque is favorably transmitted by the meshing of the external tooth 31 and the internal pin 60 . Stated another way, a configuration for lubricating the internal pin 60 can be introduced without sacrificing the ability to transmit torque to the internal pin 60 .

In addition, when viewed in the axial direction, the inclined surfaces 53 and 54 are located relative to an imaginary straight line L connecting the center point N of the circle passing on the curved surface of the first groove portion 51 and the midpoint M of the arc of the first groove portion 51. are symmetrical to each other. Therefore, the same torque can be applied to the internal pin 60 regardless of whether the speed reducer 2 is driven in the forward rotation or in the reverse rotation, and stable operation can be realized.

<3. Other modified examples>
Although exemplary embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications can be made to the above without departing from the scope of the invention. It is possible.

In the above embodiment, the second groove portion 52 (152) was provided at one location on the curved surface of the first groove portion 51 when viewed in the axial direction. However, this is not necessarily the case, and the second grooves may be provided at a plurality of locations on the curved surface of the first grooves 51 when viewed in the axial direction. However, in order to make the torque applied to the internal pin 60 the same whether the speed reducer 2 is driven in the forward rotation or in the reverse rotation, the second grooves at a plurality of locations must be aligned with the first grooves. It is desirable that they be arranged symmetrically with respect to an imaginary straight line L connecting the center point N of the circle passing on the curved surface of the groove 51 and the midpoint M of the arc of the first groove 51 .

In the above-described embodiment, the shape of the second groove when viewed in the axial direction was arcuate or triangular, but the shape is not limited to this. For example, instead of the above, the shape of the second groove when viewed in the axial direction may be rectangular or the like.

In the above-described embodiment, the second groove portion 52 (152) is formed over the entire area of the first groove portion 51 in the axial direction, but this is not necessarily the case. Alternatively, for example, the second grooves may be provided intermittently along the axial direction of the first grooves 51 .

Also, the elements appearing in the above embodiments and modifications may be appropriately combined as long as there is no contradiction.

The present application can be used for speed reducers.

1 reduction gear 10 first rotating part 20 eccentric part 30 external gear 31 external tooth 50 frame 51 first groove part 52 second groove part 59 space between internal teeth 60 internal tooth pin 70 carrier pin 80 second rotating part 91 first bearing ( bearing)

Claims (9)

An eccentric oscillating speed reducer,
a first rotating part that rotates at a first rotation speed about the central axis;
an eccentric portion arranged radially outward of the first rotating portion, rotating at the same rotational speed as the first rotating portion, and having a different distance from the central axis to the outer peripheral surface depending on the position in the circumferential direction;
an external gear arranged radially outward of the eccentric portion and having a plurality of external teeth on an outer peripheral portion;
a bearing interposed between the eccentric portion and the external gear;
a cylindrical frame disposed radially outward of the external gear and coaxial with the central axis;
a plurality of internal tooth pins held on the inner peripheral portion of the frame in a posture parallel to the axial direction and meshing with the external teeth;
a plurality of carrier pins extending axially through a plurality of through holes provided in the external gear;
a second rotating part fixed to the plurality of carrier pins;
with
The frame is
a plurality of first grooves recessed radially outward from an inner peripheral surface and extending in the axial direction for rotatably holding the internal pin;
a second groove recessed radially outward from the first groove;
A reducer. The speed reducer according to claim 1,
The speed reducer, wherein the first groove portion has an arc shape when viewed in the axial direction. The speed reducer according to claim 2,
The speed reducer, wherein the first groove is semicircular when viewed in the axial direction. The speed reducer according to claim 2 or claim 3,
The speed reducer, wherein the second groove is positioned in the middle of the arc of the first groove when viewed in the axial direction. The speed reducer according to claim 4,
The speed reducer, wherein the second groove is positioned at the midpoint of the arc of the first groove when viewed in the axial direction. The speed reducer according to any one of claims 1 to 5,
The speed reducer, wherein the second groove is formed over the entire area of the first groove in the axial direction. The speed reducer according to any one of claims 1 to 6,
The speed reducer, wherein the second groove is arc-shaped when viewed in the axial direction. A speed reducer according to claim 7,
The speed reducer, wherein the second groove is semicircular when viewed in the axial direction. The speed reducer according to any one of claims 1 to 6,
The speed reducer, wherein the second groove has a triangular shape with two inclined surfaces when viewed in the axial direction.

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